A cellulose ether is widely used as an ingredient for cleaning compositions such as a shampoo, a rinse, a treatment, and a conditioner, as well as a dispersing agent, a modifier, a flocculant, and so forth. A cellulose that is a raw material for producing cellulose ether is highly crystalline with poor reactivity, so that it is necessary to lower its crystallinity and improve its reactivity in production of the cellulose ether.
Accordingly, in a generally used production method of the cellulose ether, a cellulose is activated by a so-called alcell process or mercerization process in which a cellulose, a large quantity of water, and a large excess of an alkaline metal hydroxide are mixed as a slurry state of them to form an alkali cellulose, which is then subjected to an etherification reaction.
However, in this method, a large quantity of salt is by-produced from this large excess of the alkaline metal hydroxide used in the alcell process; and thus, the purification burden to remove this by-produced salt becomes a problem. Accordingly, methods for producing an alkali cellulose or a cellulose derivative with which the amount of the alkaline metal hydroxide is aimed to be reduced have been proposed.
For example, in Patent Document 1, a method for producing an alkali cellulose wherein a sodium hydroxide solution having a comparatively high concentration of 30 to 70% is supplied by spraying it as a mist to a pulp having the size of 60 to 80 mesh thereby effecting mixing and reacting them is disclosed.
In Patent Document 2, a method for producing an alkali cellulose wherein an alkali-substitution is done effectively by a mechanical treatment in the presence of a basic compound and water thereby having the substituent group uniformly dispersed is disclosed.
In Patent Document 3, a method for producing a cellulose derivative wherein a powder cellulose with low crystallinity is reacted with glycidol in the presence of a catalyst is disclosed.
In Patent Document 4, a method for produce a cationized cellulose wherein a powder cellulose with low crystallinity is reacted with a glycidyl trialkyl ammonium salt in the presence of a catalyst is disclosed.
In Patent Document 5, a method for producing a hydroxyalkylalkyl cellulose, wherein a pulp is treated with an alkaline metal hydroxide after the pulp is finely pulverized, and then it is reacted with an alkyleneoxide and a halogenated alkyl, is disclosed.    Patent Document 1: Japanese Patent Application Publication No. S38-4800    Patent Document 2: Japanese Patent Laid-Open Publication No. 2011-37924    Patent Document 3: Japanese Patent Laid-Open Publication No. 2009-114375    Patent Document 4: Japanese Patent Laid-Open Publication No. 2009-102587    Patent Document 5: Japanese Patent Application Laid-Open No. 2009-522394